The present invention is directed to electromagnetic apparatuses that include a core structure. The relationship between inductance and current for an electromagnetic apparatus that includes a core is a measure of the performance of the apparatus. The inductance vs. current relationship varies from apparatus to apparatus as features of the structure change, especially as the core material changes and as the gap in the core changes.
It would be useful to be able to extend the usable current range for a particular core structure and still maintain acceptable inductance vs. current performance of an electromagnetic apparatus that includes the core structure. Such an extension of usable current range for a core structure facilitates handling over-design currents (e.g., transients or high ripple). Such an extension would also facilitate an adapting saturation characteristic of the core to the optimum flat gapped core characteristic at a specific current under normal operating conditions.
The structure of the adjusting effective gap of the present invention is applicable to any gap in any material. It is most useful in ferrite cores where a hard saturation characteristic often prohibits use of such ferrite cores above a proscribed current limit. The adjusting effective gap structure of the present invention is useful for mitigating loss of inductance caused by saturation or by inappropriate gap structure and can be adapted to any core shape and size.
An electromagnetic apparatus having an adjusting effective core gap includes: (a) an electrical winding; and (b) a ferrous core situated proximal with the electrical winding. The core has a first terminus and a second terminus arranged in spaced relation to establish a gap distance between the first terminus and the second terminus in a region in substantial register with the first terminus and the second terminus. The winding and the core cooperate to establish an inductance related with an electrical current applied to the winding. At least one terminus of the first terminus and the second terminus has a configuration responsive to varying the current by effecting selective local saturation of successive portions of the at least one terminus for successive values of the current. The selective local saturation establishes successive new effective gap distances. Each respective new effective gap distance is appropriate for establishing a successive new optimum inductance for the current value then extant.
It is an object of the present invention to provide an electromagnetic apparatus having an adjusting effective core gap able to extend the usable current range for a particular core structure and still maintain acceptable inductance vs. current performance of the electromagnetic apparatus.
Further objects and features of the present invention will be apparent from the following specification and claims when considered in connection with the accompanying drawings, in which like elements are labeled using like reference numerals in the various figures, illustrating the preferred embodiments of the invention.